In recent years, a replaceable information recording medium of a large capacity and a disk drive device for driving this information recording medium are popularized.
As the replaceable information recording medium of a large capacity, an optical disk such as a DVD and a Blu-ray Disk (abbreviated as BD hereunder) is generally known. An optical disk recording/reproducing device for driving an optical disk is a device that performs recording/reproducing processing by forming an image of a minute beam spot on the optical disk by using laser beams, thereby changing physical characteristics of the information recording medium. For example, the optical disk recording/reproducing device performs recording/reproducing processing for the optical disk, being the information recording medium, by allowing the optical disk recording/reproducing device to undergo a phase change from a crystal state to an amorphous state to form a mark, etc., thereby performing recording/reproducing processing for this optical disk. The optical disk recording/reproducing device has a large capacity and is suitable for information recording that can be replaced [for example, see “120=(4, 7 Gbytes per side) and 80 mm (1, 46 Gbytes per side) DVD-Rewritable Disk (DVD-RAM)”, Standard ECMA-330, December 2001]. As the laser beams, red laser beams are used for recording/reproducing of DVD, and blue laser beams having wavelengths shorter than those of the red laser beams are used in recording/reproduction of BD. Thus, BD has a higher recording density than that of DVD, and this contributes to realizing a large capacity.
FIG. 20 is a block diagram of a recording area of a general optical disk as the information recording medium. A plurality of tracks 2 are formed on a disk-shaped optical disk 1 in a spiral form, and a plurality of finely divided blocks 3 are formed on each track 2.
Here, the width of each track 2 of BD (track pitch) is set at 0.32 μm. Each block 3 is a unit of error correction, and is a minimum unit for performing recording and reproducing operation. For example, 1ECC (size: 32 KByte) is defined for DVD, and 1 cluster (size: 64 KByte) is defined for BD. When the unit of sector (size: 2 KByte), being a minimum unit of data of the optical disk, is used for explanation, equations such as 1ECC=16 sectors, 1 cluster=32 sectors, are established. Note that in the explanation given hereunder, when the unit is described as cluster, this is the same meaning as block 3 in the BD.
FIG. 21 is a view showing a data structure in a general recording type optical disk.
The optical disk 1 is divided into a read-in area 4 on the inner circumferential side, a read-out area 6 on the outer circumferential side, and a data area 5 between them.
As shown in FIG. 21, the data area 5 is constituted, having a user data area 14, and a spare area 15 having an inner spare area 15A and an outer spare area 15B.
The user data area 14 is an area in which arbitrary information can be recorded by a user, including real time data such as music and video, and computer data such as a text and a database.
The inner spare area 15A and the outer spare area 15B, being spare areas 15, refer to alternate areas in which data is recorded instead of being recorded into a certain block 3 (see FIG. 1) in the user data area 14. The inner spare area 15A and the outer spare area 15B are areas used as the alternate areas of the block, for example, when a defective block is detected in the user data area 14. FIG. 21 is a view showing a case in which the spare areas 15 exist one by one on the inner circumferential side of the data area (namely, read-in area side) and the outer circumferential side (namely, read-out area side). Alternate recording has a merit of enhancing the reliability of data, by alternately recording data from the defective block in the user data area 14 to the block in the inner spare area 15A or the outer spare area 15B, being alternate areas. However, in the alternate recording, recording must be performed by moving (seeking) from the user data area 14, being presently accessed, to the inner spare area 15A or the outer spare area 15B, being another areas. Therefore the alternate recording has a demerit that processing time is prolonged, and recording/reproducing performance is deteriorated.
The read-in area 4 is an area arranged on the inner circumferential side from the data area 5 in a diameter direction of the optical disk 1, and the read-out area 6 is an area arranged on the outer circumferential side from the data area 5 in the diameter direction of the optical disk 1. These read-in area 4 and the read-out area 6 serve as areas in which management information, etc., regarding the optical disk 1 is stored, and over-run of optical pickup (not shown) is prevented.
The read-in area 4 includes a first defect management area 10 (abbreviated as DMA1 hereunder) and a second defect management area 11 (abbreviated as DMA2 hereunder). Both of the DMA1 and DMA2 are areas for recording management information of the optical disk 1 such as the information regarding a data structure and a defect of the optical disk 1.
The read-out area 6 includes a third defect management area 12 (abbreviated as DMA3 hereunder), and a fourth defect management area 13 (abbreviated as DMA4 hereunder). Both of the DMA3 and DMA4 are areas for recording the management information of the optical disk 1 such as the information regarding the data structure and the defect of the optical disk 1.
Although the DMA indicates the defect management area as described above in a more limited sense, it can also indicate various kinds of information (disk management information) regarding the optical disk 1, other than the defect management information. Therefore, the DMA is treated here, as the area having the meaning of a disk management area in a broad sense.
DMA1 to DMA4 thus constituted are respectively arranged at a prescribed position in the optical disk 1, and multiple recording of the same information is performed in each of the DMA1 to DMA4. This is performed in preparation for a case that any one of the DMA1 to DMA4 is defective. With this structure, even if there is the DMA that can not be reproduced correctly, the defect management information of this optical disk 1 can be acquired, provided that there is any one of the DMA1 to DMA4 that can be reproduced correctly.
The DMA1 to DMA4 has a disk definition structure 20 (abbreviated as DDS20 hereunder) and a defect list 21 (abbreviated as DFL21 hereunder), respectively (see FIG. 2).
DFL21 is the information including the information regarding alternate processing such as alternate recording performed for the defective block (alternate entry including an address of an alternate source and an address of an alternate destination, due to the defect). Here, the information regarding the alternate processing is the alternate entry including the address of the alternate source and the address of the alternate destination, due to the defect.
The address showing positional information of the block 3 of the optical disk 1 will be explained hereunder.
Generally, when access processing such as recording/reproduction is applied to the optical disk 1, control is performed by using the address physically provided on a recording layer of the optical disk 1 (physical address: abbreviated as PSN hereunder), and the address virtually and sequentially given to the area that can be accessed from a user such as a host device, namely to the data area 5, being a logic space (logical address: abbreviated as LSN hereunder). Note that these addresses are generally allocated to a sector unit or by setting prescribed numbers in the block 3 as one unit.
FIG. 22 is an explanatory view for simply explaining a relation between PSN (physical address) and LSN (logical address). Note that in FIG. 22, in order to simplify the explanation of the PSN and LSN allocated to a normal sector unit, explanation is given in a block unit.
(1) of FIG. 22 shows the relation between the PSN and LSN in the optical disk 1.
In a case of BD-RE, being a rewritable BD, the address called ADIP given to the track 2 on the optical disk 1, namely on a wall surface of a recording groove in an undulating form (wobble), and the address called AUN given to the data recorded in the block 3, correspond to the PSN. Meanwhile, LSN shows address information, and a series of numbers starting from 0 are virtually sequentially given to the LSN. As shown in (1) of FIG. 22, normally, LSN is the address sequentially allocated to all blocks 3 in the user data area 14, with its head block set at 0. Thus, the LSN at normal time corresponds to the PSN allocated to the corresponding block 3 in the user data area 14, one to one. For example, LSN=0 corresponds to PSN=A, and LSN=1 corresponds to PSN=A+1, and LSN=2 corresponds to PSN=A+2. Such a PSN (physical address) at normal time is abbreviated as offset PSN (physical address) in the explanation given hereunder.
However, for example, when a certain block in the user data area 14 is defective, and alternate recording is performed in a spare area, the LSN supposed to be allocated to the defective block in the user data area 14 is allocated to the block in the spare area used as the alternate destination.
(2) of FIG. 22 is a view showing an example of a case in which the blocks of PSN (A+2) in the user data area 14 are the defective blocks, and alternate recording is performed to the blocks of PSN (A+N+1) in the outer spare area 15B. In such a case, LSN (2) supposed to be allocated to the blocks of PSN (A+2), being the defective blocks, is allocated to the blocks of PSN (A+N+1) in the outer spare area 16, being the alternate destination. Therefore, the PSN corresponding to the LSN (2) is expressed by PSN (A+N+1). Thus, when the defective block exits, the PSN is abbreviated as an actual access PSN in the explanation given hereunder.
Therefore, in order to obtain the actual access PSN for actually accessing the data area based on the LSN requested from the host device, processing described hereunder is performed.
1) The LSN is converted into offset PSN (abbreviated as offset conversion hereunder).
2) Whether or not the offset PSN is alternate-recorded, is verified based on the DFL21.
When the offset PSN is not alternate-recorded, the offset PSN is calculated as the actual access PSN.
When the offset PSN is alternate-recorded, the PSN of the alternate destination is calculated as the actual access PSN.
A disk structure of the optical disk 1 will be simply explained hereunder, with reference to FIG. 23.
FIG. 23 is a schematic view of the optical disk 1, showing a sectional face of a recording type BD having two layers of recording layers. In the recording type BD, generally a reflective layer, a protective layer, and a recording layer are laminated on a disk substrate 50. In the recording BD shown in FIG. 23, a first protective layer 51, a first recording layer 52, an intermediate layer 53, a second recording layer 54, a second protective layer 55, and a reflective layer 56 for reflecting the laser beams are formed sequentially from its front side. The first protective layer 51 protects the first recording layer 52 for storing data, and the second protective layer 55 protects the second recording layer 54 for storing data. The intermediate layer 53 exists in between the first recording layer 52 and the second recording layer 54, having a function similar to the function of the first protective layer 51 and the second protective layer 55. The recording type BD thus constituted is irradiated with the laser beams from the front side of the disk, and recording/reproducing processing of the data is performed to the first recording layer 52 and the second recording layer 54.
As a conventional manufacturing method of BD, a method of laminating a plurality of films corresponding to each layer on the disk substrate 50 is used.
However, in the method of manufacturing the optical disk by laminating the films, the step of forming the film is required, and also the step of laminating the films is required, thus involving a problem that the manufacturing step is increased, time required for manufacture is prolonged, manufacturing cost is increased, and a price of the disk is accordingly increased. Therefore, in recent years, the manufacturing method using a spin-coat technique has been focused. Briefly speaking, the manufacturing method of the optical disk using this spin-coat technique is a technique in which film forming resin is dropped on a high speed rotating substrate, and by using a centrifugal force generated by rotation, the resin is pervaded evenly on the substrate, thus forming a recording film and a protective film.
However, the optical disk using such spin-coat technique involves a problem that air is mixed in the film such as recording layer and protective layer, namely there is a high possibility that air bubbles exists in the film. For example, when a thickness of the second protective layer 55 is 100 μm, the size of each bubbles is 100 μm at maximum when the bubbles has approximately a spherical shape, and the area where the bubbles are mixed becomes a large defective area. Further, the defective area is not applied only to the area where the bubbles are mixed, but is applied to the area where foreign matters are mixed, resulting in a large defective area in this optical disk.
When the recording/reproducing processing is performed to the optical disk thus having a large defective area, in the optical disk recording/reproducing device, normal reflected light to the laser beams can not be obtained from the area where defect such as a bubbles exists. Therefore, the block having such an area is treated as the defective block, and the data to be recorded in this defective block is alternately-recorded in the spare areas 15, being the alternate area.
FIG. 24 is a conceptual view of the optical disk 1 when the bubbles exist in the film of the optical disk 1. In the optical disk 1 shown in FIG. 24, each area shown by designation marks A to N corresponds to the block 3, and for example, one track 2 is constituted of a block A and a block B on the innermost circumferential side.
As described above, the track pitch of BD is set at 0.32 μm, and meanwhile the size of each bubble is, for example, about 100 μm. Therefore, about 300 tracks are influenced by one bubble, resulting in allowing a plurality of defective blocks to exist. In addition, as shown in FIG. 24, depending on a state of the bubbles, not only a range in which actual bubbles exists, but also the surrounding area is influenced by the bubbles, with a place where the bubbles exit set as a center, and in some cases, the defective area exists in a range of about 300 μm, which is about three times the size of the bubbles, for example. In the BD, for example in a case of the data area 5 on the inner circumferential side, as shown in FIG. 24, about two clusters (two blocks) are included in one track. Therefore, a normal cluster and a defective cluster influenced by the bubbles are mixed every other cluster. As a result, alternate recording occurs every time recording is performed to the defective cluster (defective block).
Here, in order to improve the recording/reproducing performance, a case that the optical disk recording/reproducing device has a cache function is considered. The cache function is a function of operating, for the purpose of increasing a command (request) response processing speed between the host device and the optical disk recording/reproducing device. Specifically, when reception of the recording data is completed by a cache memory provided in the optical disk recording/reproducing device, in response to a recording request from the host device, the command completed before recording is actually performed to the optical disk. Then, the optical disk recording/reproducing device realizes improvement in the command response processing speed, by performing actual recording processing to the optical disk 1 at an arbitrary timing thereafter.
In a state that the optical disk recording/reproducing device sequentially receives the data whose recording is requested from the host device such as a host PC in a cache effective state, but the data is not recorded yet, namely the data to be recorded is set in a state of still being on the cache memory, and when a reading request is given from the host device, unrecorded data held by the cache memory is recorded in the optical disk 1 and then read-out processing of the data of the requested area is performed. However, at this time, when the recording destination is the area including the bubbles as described above, the alternate recording occurs frequently, thus further increasing the processing time, and a long time is required for executing the read-out processing. In the PC (personal computer), time-out of the request (command) from the host device is normally 7 seconds, or 7.5 seconds. Therefore, in the aforementioned case, a problem is that there is a high possibility of time-out of the read-out request.
Further, there is also a case that the cluster which is impossible to be executed tracking exists, depending on a sate of the bubbles. Regarding the optical disk 1 having such a cluster, of course data recording/reproducing processing can not be performed and the AUN, being the PSN (physical address) can not be acquired, and also the reflected light by wobble given to the track 2 (recording groove) of an object cluster can not be correctly acquired. Accordingly, the ADIP address read-out by the change in the wavelengths of the reflected light can not be acquired. Therefore, there is a high possibility that the optical disk 1 is set in a state in which the PSN can not be read-out.
In order to perform fixing processing (synchronization processing) of an access position when a target address is accessed, generally, the optical disk 1 adopts a method of moving (seeking) an optical head to the area in front of the area of the target address, then by a focus servo, making the optical head reach the area of the target address along the track 2 with the help of the reflected light from the track 2 by using the rotation of the optical disk 1, and preparing for emission of the recording/reproducing laser beams from the target address. However, the reflected light from the track 2 can not be acquired by mix-in of the bubbles, thus making it impossible to execute a tracking servo, and the minute beam spot can hardly be scanned along the track 2.
Therefore, there is a possibility of occurrence of problems that as well as the cluster in which the bubbles are mixed, the other cluster that follows the cluster having the mixed bubbles can not be accessed as a result. Specifically, for example, as shown in FIG. 24, when the areas of blocks I, K, M are influenced by the bubbles, the addresses of these blocks can not be acquired, thus making it impossible to specify the present position tracked by optical beams. Therefore, there is a case that the successive blocks J, L, N can not be accessed either.
FIG. 25 is an explanatory view showing a case in which the bubbles exist in the film of the recording type BD disk (in this case, in the second protective layer 55). As shown in FIG. 25, the defect due to the bubbles and foreign matters is thereby set in a state of a swollen film. Namely, the defect in this state has a sterically concavo-convex shape. The size of such a kind of defect is about several hundreds μm at largest, and unlike a scratched scar that can be actually verified by the naked eye of a human being, it is significantly difficult to observe the aforementioned defect by the naked eye. In addition, particularly in a case of the defect due to bubbles mixing out of the defects due to mixing of foreign matters, even if the corresponding place is expanded by using a microscope, the film of the front and back area undulates like a concentric wave, with the bubbles set as the center, in an actual disk, in addition to a place of the bubbles itself that can be actually visually observed. Therefore, there is a significantly high possibility that even the area around the bubbles also becomes the defective area that can not be accessed in performing the recording/reproducing processing. Namely, a size of a range of the defective area due to the bubbles corresponds to a total size of the size of the bubbles itself having a visible solid shape and about the same size of the bubbles in the back and forth of these bubbles. In other words, the size of the defective area due to the bubbles is about three times the size of the bubbles having a solid shape.
In the optical disk recording/reproducing device that performs recording/reproducing processing to aforementioned optical disk, a normal reflected light to the laser beams can not be obtained from the area in which the defect such as bubbles exist. Therefore this area is treated as the defective block, and the data is alternately recorded in the spare areas, being the alternate areas, by the optical disk recording/reproducing device, the data being supposed to be originally recorded in this defective block.
In addition, as shown in FIG. 25, in a case of a multi-layer disk having a plurality of recording layers, when the bubbles exist in the film of the optical disk, particularly between a disk surface, being the side irradiated with the laser beams and the reflective layer 56 for reflecting the irradiated laser beams, access fails to the area corresponding to a position of almost the same radius as that of the position where the bubbles exist, in not only the second recording layer 54 close to the bubbles but also in the first recording layer 52, being the other recording layer. Namely, the area becomes the defective area in each recording layer, by existence of one bubble.
Each kind of technique is proposed in a field of a defect management method in a conventional optical disk recording/reproducing device, in order to respond to an unfavorable circumstance such as an existence of the defective block when the tracking servo is executed based on a recording signal. For example, as an example of the defect management method, there is a technique in which the area including the defective block and a subsequent prescribed range is treated as the defective area, and information of a list of this defective area is registered, and when reproducing operation is performed, avoiding access to the defective area, the alternate destination is to be accessed, thereby making it possible to perform reproducing operation without being influenced by the defective block. This technique is disclosed, for example, in Japanese Patent Laid Open Publication No. 2002-184116.    Patent Document Japanese Patent Laid Open Publication No. 2002-184116    Non-patent Document 1: 120 mm (4, 7 Gbytes per side) and 80 mm (1, 46 Gbytes per side) DVD-Rewritable Disk (DVD-RAM)2, Standard ECMA-330, December 2001